As I understand, 我有一辆汽车, if it comes on its own, would mean "I have one car".
Adding 而已 (i.e. 我有一辆汽车而已) would make it something like: "I have one car and that's it".
Adding 只 （i.e. 我只有一辆汽车) would make it: "I only have one car". The difference here would be similar to the difference between "I have one car" and "I only have one car". In both cases the ...
The differences are contextual. I do agree it is very subtle.
到 is used when the verb, (action), produces a response from a purely physical perspective. Whereas, 了 is from a non-physical moral, legal, ethical standpoint.
So, in 收不到 vs 收不了, the former connotes the physical impossibility of receiving whatever is sent, perhaps it was physically destroyed ...
It's all joking lah!
The translation of a nation name is often chosen according to its sound, but Chinese characters have their own meanings as well, so you can indeed explain it somehow that way, which has nothing to do with the characteristics of that nation.
英国 Britain：英勇之国 the nation of bravery
法国 France：律法之国 the nation of law
德国 Germany：美德之国 the ...
As a Taiwanese, I'd say most of the people here don't really think it through when being asked a question as such. For most of the Taiwanese (except those who study languages /history/culture in grad school I guess), the word "Chinese"(中文) is pretty much the same as "Mandarin" (國語) (Yeah, not "国语" or "普通话", that's how PRC people call it)
At school, Our "...
If you were to say someone owned a car, you would call him a 车主 (of the car).
If you were to say someone only had one car, you would say “他只有一辆车。”
If you were to say someone had at least one car, you might say “他至少有一辆车。”
Quote：- “。。。how would one instead specify that they have exactly one car?"
而已 = that's all; nothing more.
Because the Chinese language does not have plurals but quantifiers, you have no choice but to use words like 几个, 几辆 to indicate " a few or several"
So, 我有几辆汽车 -- I have a few / several cars.